Rev vs Modern Robotics (MR) Electroinics?

Has anyone done a comparison of the electronics between Rev & MR?

I am revamping a FTC team and they have the MR electronics, but need to purchase some new equipment.

Thoughts/suggestions.

Do not buy new Modern Electronics. Only buy REV. It is the future of FTC.
The many USB connections on MR is unreliable compared to just 1 for REV. Less cable management will be needed as EVERYTHING can go right to the REV Expansion Hub. REV can also be purchased at a good discount in the FIRST storefront.

That said, if you are short on cash, currently owned MR will do fine, but replace it with REV as soon as you can afford it after registration.

Yes to all of this. We just converted all of our FTC to Rev and the difference is notable.

Straight up, once MR is officially not allowed in FTC, the competition will be better off. REV is better in basically every measurable way. It is more reliable, more compact, and just generally better designed. The vast majority of teams I needed to help at Detroit (I was a CSA for FTC) were teams that used Modern Robotics.

I might not put it as the immediate first thing after registration fees–I would probably put it just behind field elements and getting away from TETRIX round-bore hubs.

But I would make it a priority, as “don’t buy new MR stuff” is gonna burn pretty badly if you break something two weeks before your tournament and have to choose between converting everything on the spot (if parts are even available–I’m not a REV hater, but that is sometimes a challenge for them) and shelling out cash on a platform that is clearly fading. Better to go ahead and plan that migration out.

Most of our FTC teams switched to REV this year with decent success. We did have a couple of the hubs that failed some output channels, but for the most part, they were rock solid. I was a bit worried at the beginning of the year because no one had designed and 3D printed any strain relief cord holders for the USB cords. Those were an absolute must for the MR gear to avoid DCs, but we never had any issues with the REV equipment. It was a bit annoying to have to change all of our power cords to the REV style connectors, but we built a bunch of jumper cords with powerpoles on the other end so that we could use the existing powerpole connectors that were already on our motors from previous years.

My biggest gripe is that the REV hub is equipped to handle exactly half of the allowed motors and servos. So most of our teams ended up using 2 hubs connected together. The big problem with this is that you are basically duplicating a bunch of stuff you don’t need in order to get the extra motor controllers and servo drivers. You could use the MR gear in parallel with the REV hubs, but that gets messy. I don’t understand why they could not just make a single REV module that could handle the FTC maximums of 8 motors and 12 servos so that the teams could keep adding on to their robot without needing to find space for a second hub midway through the build season as they added mechanisms that needed more control than the single REV hub could handle. FIRST spec’d out the box for REV. I know they were trying to keep the cost down for the average teams, but it ended up being more expensive if you needed to get 2. Why couldn’t they spec a REV Hub Lite (the current design) which could be cheaper and a REV Hub Max that would be a bit more expensive, but less than the cost of 2 Hubs because you would not need to duplicate the smarts in order to add the additional channels.

There are technical limitations that don’t make doing a super hub easy. Heat dissipation of all the motors and servos would drive the size of the hub to just about the same size of two. A larger main chip to drive all the extra IO would be significantly more expensive as we would have to really step up in the class of components. All of this are things that were looked at during the design but the justifications for the engineering and cost trade offs were not there to support that design. $300 as an all in cost for two hubs is still a significant cost savings over a maxed out MR system.

There are things in the works that will provide some additional options in the future, and we always take feedback from teams as we move forward with future product development.

Hey, thanks for the explanation!

I had asked about this with the REV rep at one of our competitions and they only were able to tell me about the desire to keep the cost down for typical teams. It’s actually good to know that there were technical limitations that were considered when deciding not to go with such an obvious configuration. There is a bunch of cool stuff built in to each hub that you really only need one of. So, it seemed like overkill to carry a second one on the bot. But at the end of the day, if you are maxing out an FTC bot in terms of motors and servos, you are right that the $350 for two hubs is very good for all that functionality. For a bot that needs 6 motors (no servos) the REV system is only slightly more expensive than the MR configuration.

We never had any issues linking the two hubs together (once we figured out how to name them correctly - thanks to the REV technical team near the start of the season). We had a lot less issues with the REV hubs than we seemed to have with the MR gear over the years which made this past season a lot lower drama than previous years.

I do highly recommend moving to the REV system to other FTC mentors that I talk with at our local competitions. Many of them are reluctant to spend the money to buy 2 hubs, but many of them have bought one hub and use it in conjunction with their MR components and intend to invest in a second hub at some point in the future.

Now if we can only find a solution to the static electricity issue…

My team went with MR this year and to say that it was a mistake is an understatement.

The most obvious reason to go with REV is the smaller area the REV hubs take. If you want to use all of your motors/servos/sensors, MR will need 1 Core Power Distribution, 4 Motor Controllers, 2 Servo Controllers, and 1 Sensor Block. REV only needs 2 hubs (about the size of the CPD). This greatly reduces the space you need for electronics, as well as all the cables connecting the motor controllers.

The biggest reason why we’re switching to REV is the reliability. We’ve had issues with MR is the past, but this year took the cake. I’m not exaggerating when I say that our robot sat dead on the field for half of our matches. We had all of the wires secured in place, but any good shake would disable us for the match. Some CPDs were decent, but we had to replace ours 3 times.

All in all, go REV. There is no reason to use MR at this point.

Just hold on, things are coming that I promise you will like. :wink: